1. Field of the Invention
The invention relates to new colorant compositions, and to methods of forming and using such colorants. In particular applications, the invention pertains to phase change ink formulations.
2. Description of the Relevant Art
The present invention encompasses new colorant compounds, routes to their preparation, and methodology for incorporating such compounds into phase change inks. Phase change inks are compositions which are in a solid phase at ambient temperature, but which exist in a liquid phase at an elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device. When the ink droplets contact the surface of a printing media, they solidify to form a printed pattern. Phase change ink methodology is described generally in U.S. Pat. Nos. 4,889,560; 5,372,852 and 5,827,918.
A definition which will be adopted in this disclosure and the claims that follow will be to utilize the term “colorant” to refer to modified dyes, chromophores and pigments which are suitable for inclusion in phase change inks. Another definition which will be adopted in this disclosure and the claims that follow will be to refer to a phase change ink composition as comprising a colorant and a carrier. The term “carrier” is to be understood to comprise all components of a phase change ink composition with the exception of the colorant. In phase change ink compositions comprising more than one colorant, the carrier will include everything except a particular colorant of interest, and can, therefore, comprise colorants other than that which is of interest.
A difficulty associated with phase change inks can be in solubilizing traditionally utilized dyes, chromophores and pigments. Many colored compounds useful in producing phase change inks for digital printing generally comprise polar functional groups, and accordingly are insoluble in the organic carrier of a phase change ink composition. The solubility of the colored compounds can be improved by increasing the hydrophobic character of the colored compounds. Accordingly, it is desirable to develop methods for increasing the hydrophobic character of existing chromophores, dyes and pigments to produce new colored compounds, as well as to develop new colorants with substantial hydrophobic character.